This study shows that the type of the inflammatory infiltrate in lung tissue of patients with UIP/IPF was predominantly mononuclear, and that among the different inflammatory cells, CD8+ TLs correlated significantly with both functional [FVC, TLC, DLCO, PaO2, P(A-a)O2] and clinical indices (the MRC chronic dyspnoea score) of the disease severity and extent studied and macrophages (CD68+ cells) with some of the functional indices studied (FVC and FEV1). Here, CD68 is linked to idiopathic pulmonary fibrosis.